The invention relates, furthermore, to a battery unit for application in such an apparatus. The invention relates additionally to an operating electronics for application in such an apparatus. The invention relates, moreover, to a field device of process automation technology, especially a radio unit, having such an apparatus.
In process automation technology as well as in manufacturing automation technology, field devices are often applied, which serve for registering and/or influencing process variables. Serving for registering process variables are measuring devices, respectively sensors, such as, for example, fill level measuring devices, flow measuring devices, pressure- and temperature measuring devices, pH, redox potential measuring devices, conductivity measuring devices, etc., which register the corresponding process variables, fill level, flow, pressure, temperature, pH-value, and conductivity. Serving for influencing process variables are actuators, such as, for example, valves or pumps, via which the flow of a liquid in a section of pipeline, or the fill level in a container, can be changed.
Referred to as field devices are, in principle, all devices, which are applied near to the process and which deliver, or process, information relevant to the process. Besides the above mentioned measuring devices/sensors and actuators, also referred to as field devices are generally units, which are connected directly to a fieldbus and serve for communication with superordinated units, such as e.g. remote I/Os, gateways, linking devices and radio units. A large number of such field devices are produced and sold by the firm, Endress+Hauser.
In modern industrial plants, field devices are, as a rule, connected via bus systems (Profibus®, Foundation Fieldbus®, HART®, etc.) with superordinated units. Normally, the superordinated units involve control systems, or control units, such as, for example, a PLC (programmable logic controller). Superordinated units serve, among others things, for process control, process visualizing, process monitoring as well as for start-up of the field devices. The measured values registered by the field devices, especially by sensors, are transmitted via the connected bus system to one, or, in given cases, also a number of, superordinated unit(s). Along with that, also data transmission from the superordinated unit via the bus system to the field devices is required; this serves especially for configuring and parametering field devices or for diagnostic purposes. In general, the field device is serviced via the bus system from the superordinated unit.
Besides a wired data transmission between the field devices and the superordinated unit, there is also the opportunity for wireless (wireless) data transmission. Especially, in the bus systems Profibus®, Foundation Fieldbus® and HART®, a wireless data transmission via radio is specified. Furthermore, radio, or wireless, networks for sensors are specified in greater detail in the standard IEEE 802.15.4.
For implementing wireless data transmission, newer field devices, especially sensors and actuators, can be embodied as radio field devices. These have, as a rule, a radio unit and an electrical current source as integral components. In such case, the radio unit and the electrical current source can be provided in the field device or in a radio unit connected durably to the field device. The electrical current source enables an autarkic energy supply of the field device.
Along with that, there is the opportunity for retrofitting field devices that do not have internal radio units—thus the installed base—to become radio field devices by externally providing them with at least one radio unit. A corresponding radio unit is described, for example, in the publication WO 2005/103851 A1. The radio unit is, as a rule, connected releasably to a fieldbus communication interface of the field device. Via the fieldbus communication interface, the field device can transmit to the radio unit the data to be transferred via the bus system. The radio unit then transmits the data via radio to the target location. Conversely, the radio unit can receive data via radio and forward such via the fieldbus communication interface to the field device. The supplying of the field device with electrical power occurs then, as a rule, via an energy supply unit of the radio unit.
In the case of autarkic radio field devices with or without external radio unit, communication, for example, with a superordinated unit, is conducted, as a rule, via the wireless interface of the radio field device, or the external radio unit, as the case may be. Additionally, such radio field devices, respectively radio units, have, as a rule, a wired communication interface. For example, it is provided in the HART® standard that radio field devices must have, besides a wireless interface, also a wired communication interface. Via such a wired communication interface, for example, on-site, a configuration of the radio field device, respectively the radio unit, is possible via a service unit, such as, for example, a handheld communicator, which is connected to the wired communication interface. Furthermore, the wired communication interface can be embodied as a fieldbus communication interface, so that the communication is conducted thereby in accordance with a bus system, such as, for example, one of the standardized bus systems, Profibus®, Foundation Fieldbus® or HART®. Via such a fieldbus communication interface, the radio field device, or the radio unit, can also be connected to a corresponding wired fieldbus.
These field devices, respectively radio units, have electronics, i.e. electronic units, for performing their functions and functionalities. These electronic units have, for example, programs or algorithms, by which the corresponding functions are executed. To this end, the electronics unit requires a certain amount of electrical energy. The energy supply unit, respectively the electrical current source, of a radio unit, a field device or a radio field device is usually a battery. Known from Offenlegungsschrifts (laid-open German applications), DE 102008036554 A1, DE 102008037193 A1, DE 200810038415 A1 are such battery units, which are applied preferably in process automation. The term, battery, means, in such case, generally, besides a galvanic cell, also other energy storage units, such as, for example, a rechargeable battery.
Furthermore, it is also usual to connect the battery via cable with the corresponding electronics unit, which in the case of a field device, is also referred to as the operating electronics. A contacting of the battery occurs then preferably first in the case of start-up of a corresponding field device, i.e. the cable is, during storage and transport, not connected with the electronics unit, respectively the battery. Cables with a coupling and/or corresponding plug are, however, exactly in the case of frequent use, not robust enough and can be easily damaged.
The aforementioned battery units are, in the case of field devices, moreover, only equipped with an, especially symmetric, preferably centrally arranged, contacting. Such battery units use, however, due to their construction, only one possible installed position, in which they can be connected with the electronics unit and/or applied in a housing.
Due to safety concerns and constraints, the battery unit must be transported isolated from the associated device. Additionally, for certain transport paths, e.g. in the case of transport by means of airplane, the particular device is not permitted to be turned on during the transport.
Furthermore, it is disadvantageous in the case of the solutions known from the state of the art that after the contacting there is always a certain discharge current, which leads to a lessened service life of the battery and thus of the respective device.
Known from the state of the art, especially from international application WO 2006/027284 A1, is an apparatus for locking electrical and electronic devices with battery packs for electrical current supply. A two stage locking of the disposable battery pack is provided, wherein in a first installed position still no contact occurs between the connections of the battery pack and the provided, electrical, electronic tool and wherein electrical contact is produced only in a second installed position, which is produced by pushing the battery pack into the electrical, electronic tool. Since the contacting occurs by pushing the disposable battery pack in, however, this means that, in WO 2006/027284 A1, sufficient space must be provided for at least two installed positions. This is, however, exactly in the case of devices, in which the battery unit is accommodated completely in a housing, often not possible. Furthermore, in the case of WO 2006/027284, the battery must be accessible from the outside or the housing must be opened.